Optus seems to have increased the wholesale cost of 4G mobile data.
My current $70 per month 200GB plan with Optus is expiring.
This is the cheapest one now for 250GB of 4G data via the Optus network. It is also unshaped (unlike others which limit you to 12/1). I get 40/20 usually.
Viable NBN replacement for some, especially if you are still waiting for a connection, having issues with HFC or prefer the mobility of a 4G connection.